Magnetic glass-ceramics

Abstract

Abstract:We present the magnetic properties of magnetic glass ceramics obtained by crystallization of Fe containing borosilicate glass. Two types of nucleators have been used: Cr 2 O 3 and P 2 O 5 . The role of the nucleators proved to be crucial in the size and morphology of the crystallites developed within glassy matrix as well in the magnetic response. The former stimulates the growth of regular single crystals uniformly dispersed within the matrix whereas the latter leads to the formation of grains made of tiny (30 nm), nanocrystals. The magnetic response depends on the amount of Fe ions left dispersed within glassy matrix as paramagnetic ions. Although P 2 O 5 leads to the best structural magnetite, almost 42% of Fe ions are left dispersed in the matrix without magnetic interaction. In the case of Cr 2 O 3 , the paramagnetic Fe is decreased to 12% but structural deficiency in the occupancy of the Fe sites of magnetite is revealed by Mössbauer spectroscopy.

Magnetic properties of glass-ceramics obtained by crystallization of iron-rich borosilicate glasses

“…However, despite the wide compositional possibilities, only a few types of magnetic glass-ceramics with silicate or borosilicate glass parent were reported. Most of them are related to magnetite-based glass-ceramics [3][4][5][6][7][8][9][10][11][12] and BaFe 12 O 19 [13][14][15][16][17][18][19][20] but also SrFe 12 O 19 [21][22][23][24][25] and MgFe 2 O 4 [26]. In addition to the oxidic ingredients used for the fabrication of the parent glass, the nature of the nucleating agents seems to be highly relevant to the magnetic properties of the resulting glass-ceramics as well because they facilitate/inhibit the formation of certain phases and impose a specific growth pattern.…”

Synthesis and properties of ferrimagnetic glass‐ceramics and glass fibers derived from pyrite slag

“…The low‐magnified TEM images (Figure A,D and G,J) show that some small dark particles were embedded in amorphous phase, indicating the presence of spontaneously crystallized magnetite crystals in glass matrix. The average particle size is about 30 nm . The high‐magnified TEM images (Figure B,E and H,K) illustrate the periodic fringe spacing of 0.25 nm which corresponds to the (311) plane of cubic Fe 3 O 4 .…”

Recycling of inorganic waste in monolithic and cellular glass‐based materials for structural and functional applications

“…Iron‐rich ceramic phases, such as magnetite and other ferrites (oxides with the general formula M 2+ Fe 2 O 4 , or M 2+ O · Fe 2 O 3 ; magnetite, Fe 3 O 4 , may be expressed as FeO · Fe 2 O 3 ) are well known for their ferrimagnetic behaviour . Considering the great availability of iron in waste‐derived glasses, and the limited solubility of iron oxides in glasses, as stated above, it is not surprising to find ferrimagnetic phases in waste‐derived glass‐ceramics.…”